Again, those are what Blue is associated with. it's not necessarily water or air magic. The page also says it's about deceit, logic, illusion, knowledge, and information. Even think about the guilds with blue in Ravnica. Azorius' blue is more about controlling their opponents, Izzet's blue is usually to manipulate the board and cripple you're opponent's decisions, Dimir's blue is about mill and manipulation (keep in mind the deck is the equivalent of your mind), and Simic uses blue to alter the board/creatures. What do they have in common? manipulation, control, and generally crippling your opponent's ability to play their cards.
Water and air may be a common theme in the cards but they're not what blue is about.